Modeling the Motor Current for Harmonic Reducer Faults of Industrial Robot under Service Conditions

doi:10.3901/JME.2025.18.366

Abstract

Abstract: Harmonic drives are commonly employed in the joints of robotics, where they facilitate power transmission driven by servomotors. The flexible thin-walled bearing, an important component of harmonic drives, is susceptible to failures under the cyclic squeezing and alternative load conditions of cam, and it generates harmonics in the current of the connected motor. However, the operation conditions of robots can induce non-stationary changes in fault frequencies, coupled with the frequencies induced by the structural deformation of the flexible bearing, which makes the modulation effects of fault on current complicated. The stator current model for different faults in the flexible thin-walled bearing of harmonic drives is proposed. This model accounts for the effects of varying speed and load conditions, the frequencies due to variations of the long and short axes of the flexible thin-walled bearing, and the fault frequencies into the current model. By establishing a simulated experiment platform of harmonic drive with different faults, the tests under constant speed and load, constant speed varying load, variable speed constant load, and variable load variable speed conditions are conducted to validate the applicability and accuracy of the established current model considering fault on different part of the flexible thin walled bearing.

Key words: fault modeling, current signal, industrial robot, harmonic reducer, variable speed and load condition

CLC Number:

TG156

WANG Jia, GE Manzhe, WANG Ziming, ZHANG Luyu, WANG Chongshuai. Modeling the Motor Current for Harmonic Reducer Faults of Industrial Robot under Service Conditions[J]. Journal of Mechanical Engineering, 2025, 61(18): 366-377.

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